Effect of 5-FU alone and IFN-α, IFN/5-FU on apoptosis of HUVEC. (A) TUNEL assay showed limited number of TUNEL-positive cells in each treatment. (B) IFN/5-FU did not induce apoptosis of HUVEC in annexin-V assay. The percentage of Annexin-V positive cells is shown in figures. (C) Serum-free CM from control culture of HuH-7 significantly promoted HUVEC growth. Supernatants from HuH-7 treated by IFN-α (500 units/ml) and 5-FU (0.5 μg/ml) (CM-IFN/5-FU) significantly inhibited the growth of HUVEC. (D) Growth inhibition of CM-IFN/5-FU was due to induction of apoptosis. The number of TUNEL-positive cells in CM-IFN/5-FU was significantly higher than in other conditioned media (Figure 4D).